I have a .44 Marlin and have shot both the pistol cartridge range and the center fire silhouette matches. The difficulties I found came from the two opposite ends of the power curve...
1. Plan on shooting different loads for the 2 matches.
2. JHP bullets will do less damage than the hard cast lead bullets.
3. Accuracy does increase when shooting bullets faster than the very light .44 spl. loads I have been shooting (1200 fps), but the recoil increases also. We have some target damage problems on the hunter pistol targets with the true .44 mag loads. We found some target dimpling with light loaded lead bullets also.
I have been able to shoot 2-3" groups at the 100 meter distance, iron sights. My best scores have been 53,52,50,49/60 using this .44 marlin rifle. 200gr Ranier HP, 5 gr. Titegroup in a .44 spl case, is my current hunter pistol cartridge load.
If I did not have this rifle and was looking for one to play these games, I would purchase a .357 Marlin. Get the longest barrel they have.